1. Field of the Invention
The present invention relates to identification of elongate objects using indicia wherein a mark is both rendered permanent and protected using an optically clear means of attachment.
2. Description of the Related Art
It is frequently necessary to identify components in electrical assemblies, particularly where a multiplicity of wires and/or cables need to be identified. Various marking systems for wire cables and the like are known in the art.
Wires and cables have been identified by impressing characters into the insulation surrounding the wire. This has the disadvantage of possible damage to the insulation. Early attempts to create permanent marking assemblies employed plastic tubes which slip over the cable. These may be loose or may use heat-shrink technology as disclosed in U.S. Pat. No. 3,894,731. However, these assemblies require application during installation, since they must be slipped onto or over an unterminated wire. This limits any marking of already installed cable, or redesignation.
Later, heat-shrink sleeves were formed as wrap-around versions, which employed strips of heat-shrink film. It is necessary to secure the final "wrap" to prevent the formation of a free end. This is known in the industry as flagging. However, both tubular and wrap-around shrink sleeves employ radial shrinkage. The identification is usually printed or typed onto the article, and rendered permanent by a heat treatment. This is referred to as "permatization", and may be accomplished by heating in an oven or subjecting to infrared radiation. This is expensive, and may not be effective for elongate articles which are dark in color.
U.S. Pat. No. 4,569,759, (Brewers) discloses an adhesive tape construction used for identification markers to be applied to wire cables or switch structures. A pressure-sensitive adhesive layer is applied to the lower surface of a transparent substrate, which has an opaque ink-receptive area. The tape is cut into individual strips which are adhesively attached side-by-side on a release carrier material. The information is inscribed on the ink-receptive area. The marker strip is then removed from the release liner by peeling back the tape, and applied by attaching the head section to the wire and wrapping it upon itself so that the width dimension of the tape becomes the length of the marker. Multiple layers of strips may be arranged upon one another.
U.S. Pat. No. 4,465,717, (Crofts et al.) discloses a means for marking elongate objects in which a carrier supports a strip of marking material consisting of a heat-shrink film coated with a heat-reactive adhesive. Two stripes of pressure-sensitive adhesive are applied to the heat-reactive adhesive. The identification is then applied to the strip on the surface opposite to that holding the adhesive. The marker is imprinted and applied temporarily via the pressure-sensitive adhesive. Permanent attachment is achieved by applying heat which activates the heat-reactive adhesive and shrinks the sleeve.
U.S. Pat. No. 4,246,709, (Selleslags) discloses a holder for an identification sheet which comprises two transparent films bonded by their side edges. When heated, the composite curls relative to a single axis. For use, the identification is added as a sheet between the two films. The composite is then applied and heated, whereupon it curls around the wire until it conforms. A hot-melt adhesive may be used to attach the identification permanently to the wire.
U.S. Pat. No. 4,868,023, (Ryan et al) discloses indicia which are applied to a polyolefin surface using a pigmented ink, which cures at elevated temperatures to provide a permanent mark.
It has now been discovered that a marking article may be formed via wrap-around techniques to provide either a temporary or a permanent marker. This marker is flag-free and has permanent readability due to protection afforded by an optically clear wrap of the article.
Further, because the polymeric film used in the article is dimensionally stable, the imprinted area does not suffer from distortion of the markings thereon.